In the past, as a material kneading apparatus that continuously kneads a material to be kneaded such as plastics, a twin screw extruder has been known.
The twin screw extruder has a cylindrical cylinder, and two screws inserted into the cylinder so as to be in parallel with an axial direction of the cylinder and with each other. Each of the screws is rotatably supported at both ends on the upstream side and the downstream side in the cylinder, and has a kneading blade formed helically therein, the kneading blade sending the material to be kneaded. A motor is linked to an upstream side end portion of each screw, via a reducer. Each screw is rotated by the motor, which then rotates the kneading blades. With these rotations, the material to be kneaded, which has been loaded into the cylinder, is sent from the upstream side toward the downstream side, thereby to be kneaded, and then sent out to a granulating apparatus at the subsequent stage.
The twin screw extruder is configured of a transporting portion, a melt-kneading portion, a volatilizing-off portion, and a discharging portion, from the upstream side toward the downstream side. The melt-kneading portion has a kneading element where a sending blade, which is a kneading blade that sends the material to be kneaded toward the downstream side, is formed on the screw, and another kneading element that is provided on the downstream side with respect to the aforementioned kneading element and where a returning blade, which is a kneading blade that returns the material to be kneaded toward the upstream side, is formed on the screw. In the following, operations of the twin screw extruder will be briefly explained.
First, in the twin screw extruder, the motor is driven based on an input or the like from a user. With the drive of the motor, the twin screw extruder rotates screws in opposite directions to each other, thereby to rotate the kneading blades provided on the corresponding screws. With these rotations, in the transporting portion, the material to be kneaded, which has been loaded from a material loading opening provided in the cylinder, is sent out to the melt-kneading portion. In the melt-kneading portion, the material to be kneaded, which has been sent out from the transporting portion, is melted and kneaded by the rotating sending blade and returning blade, and then sent to the volatilizing-off portion. In the volatilizing-off portion, a so-called volatilization-off of gases or the like is performed, where the gases or the like, which have been generated when the material to be kneaded is melted and kneaded, are exhausted from a ventilation opening provided in the cylinder. Also, the material to be kneaded, which have been melted and kneaded (referred to as a melted material hereinafter), is sent out to the discharging portion. Next, in the discharging portion, the melted material is discharged from a material discharging opening provided in the cylinder.
Incidentally, as related art, the following patent literatures or the like are known.